In order to meet increasing wireless data traffic demand in wireless communication systems, efforts have been made to develop beyond 4G network, post-LTE, enhanced fifth-generation (5g), and pre-5G systems.
These enhanced systems are being taken into account on ultra-high frequency (mmWave) bands, in particular, a 60 GHz band, and such techniques are under discussion as beamforming, massive array multiple input multiple output (MIMO), full-dimensional multiple input multiple output (FD-MIMO), array antennas, analog beamforming, and large-scale antennas.
Also being developed are various technologies to have an enhanced network, such as evolved or advanced small cell, cloud radio access network (cloud RAN), ultra-dense network, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-point (CoMP), and interference cancellation.
There are also other various schemes under development for the 5G system including, e.g., hybrid FSK and QAM modulation (FQAM) and sliding window superposition coding (SWSC), which are advanced coding modulation (ACM) schemes, and filter bank multi-carrier (FBMC), non-orthogonal multiple access (NOMA) and sparse code multiple access (SCMA), which are advanced access schemes.
Wireless communication systems are being developed in various types to deliver voice and/or data. A typical wireless communication system or network provides various multiplexing techniques, including frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and orthogonal frequency division multiplexing (OFDM), to allow multiple users to access one shared resource.
Cellular wireless communication systems provide multiple base stations (BSs), access points (APs), Node Bs (NBs), and enhanced Node Bs (eNBs) for a coverage area. The base stations have their respective unique coverage areas (i.e., cells or sectors) that may overlap each other that terminals (mobile stations (MSs), user equipment (UE), wireless terminals, or mobile devices) may independently receive. Likewise, a terminal may transmit data to the base station operating the coverage area of the terminal or to another terminal in a similar manner. In next-generation communication systems, the cell size gradually reduces due to inter-cell interference, and interference signals from neighbor cells become a major cause for a degradation in the efficiency of detecting desired signals.
A representative technique for interference mitigation is interference-aware successive decoding (IASD). The IASD has been developed to address problems at the cell edge in cellular system, adopting the concept of interference-aware receiver capable of successfully decoding both desired signals and interference signals. Since interference signals are out of the control by the terminal, the IASD requires support by the network. In order to avail cellular system of the IASD, network assisted interference cancellation and suppression (NAICS) is being discussed. NAICS allows an interference signal and desired signal to be transmitted through the same resource and provides signaling and channel estimation information from the network to decode and detect interference signals.
The IASD may advantageously be implemented at a relatively low complexity because of avoiding simultaneous decoding involving a high complexity, but for the same reason, its performance may be greatly far away from the Shannon limit that is theoretically known to be the maximum information transmission speed. This leads to the need for technology for addressing a deterioration of receive performance in terminals at cell edges due to interference by neighbor cells and achieving the maximum theoretical performance of the physical layer in such interference circumstances.